Variable section interlocking structural panel

ABSTRACT

An interlockable structural panel with a channel cross-section including a base and first and second side wall forming the sides of the channel, wherein an end of the first side wall distal the base is curved as a first arc directed away from a central portion of the channel and an end of the second side wall is curved as a second arc directed towards the central portion of the channel and wherein a straight section extends from the end of the second arc distal the base. Also methods for forming interlockable structural panels and for forming curved interlockable structural panels for constructions including roofs.

FIELD OF THE INVENTION

This invention relates to panels which interlock to form self-supporting roofs of buildings, in particular large span roofs supported only by the walls of the building.

BACKGROUND OF THE INVENTION

Interlocking panels for large span roofs have been in use for some time. One of the most successful such panels is disclosed in U.S. Pat. No. 4,759,159 as having a pair of upstanding flanges at opposite longitudinal sides, a male rib supported by one flange and a female rib supported by the other flange, both the male and female ribs extending wholly to one side of their supporting flanges, the male rib engageable with the female rib of an adjacent panel to form an arcuate self-supporting roof section for a building.

The female rib is defined as being of generally inverted U-shape form in transverse cross-section having a first leg comprising an extension of said supporting flange and a second leg spaced from said first leg, said second leg having a at its free end, an inwardly directed first deformation and there being provided a second deformation in the region of the junction between said first leg and said supporting flange.

The male rib is defined as being generally of an inverted U-shape form in transverse cross-section having a first leg comprising an extension of said supporting flange and a second leg spaced from said first leg and inclined outwardly away from said first leg, and there being an inwardly directed projection defining a recess in the region of the junction between said first leg and said supporting flange being complementary to said second deformation such that when interlocked said male rib is located within said female rib, said first legs of said male and female ribs are juxtaposed, said second leg of said male rib resiliently engages said second leg of said female rib rearward of said first deformation and said second deformation nests within said recess.

These known panels are formed in longitudinally curved sections and erected and joined to form self-supporting roofs as shown in FIG. 1 of the drawings. However the nesting geometry of the inverted U-shapes is quite unforgiving of any deformation of the cross-section of the panel and the male rib tends to spring out of the female rib when the panel is flattened. The common solution to this has been to fasten the female rib to the male rib with screws which defeats the self-interlocking of adjoining panels and adds to the cost of construction.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome or ameliorate at least one or more of the disadvantages of the prior art, or to provide a useful alternative.

Throughout this specification, unless the context requires otherwise, the words “comprise”, “comprises” and “comprising” will be understood to imply the inclusion of a stated step or element or group of steps or elements but not the exclusion of any other step or element or group of steps or elements.

Any one of the terms: “including” or “which includes” or “that includes” as used herein is also an open term that also means including at least the elements/features that follow the term, but not excluding others. Thus, “including” is synonymous with and means “comprising”.

In the claims, as well as in the summary above and the description below, all transitional phrases such as “comprising”, “including”, “carrying”, “having”, “containing”, “involving”, “holding”, “composed of”, and the like are to be understood to be open-ended, i.e. to mean “including but not limited to”. Only the transitional phrases “consisting of” and “consisting essentially of” alone shall be closed or semi-closed transitional phrases, respectively.

Arrangements of the present invention provides an interlockable structural panel comprising a channel cross-section including a base and first and second side wall forming the sides of the channel.

According to a first aspect of the invention, there is provided an interlockable structural panel for forming roofs with a channel cross-section including:

-   -   a base and first and second side walls forming the sides of the         channel; wherein the first and second side walls mirror each         other's extension from the base and provide a generally straight         extension from the base;     -   wherein a region adjoining an end of the first side wall distal         the base is curved as a first arc directed away from a central         portion of the channel and a section adjoining an end of the         second side wall is curved as a second arc directed towards the         central portion of the channel;     -   wherein a straight section extends from a distal end of the         second arc;     -   wherein the end of the first arc comprises a projection, a         distal tip of the projection extending towards the first side         wall;     -   wherein the second side wall comprises at least first and second         intermediate arcs extending from a generally horizontal section         of the second sidewall and through a generally vertical section         of the second side wall intermediate the first and second         intermediate arcs; and     -   wherein the structural panel includes mateable portions arranged         to engage with identical first and second arcs of an adjacent         identical structural panel in a locking manner without deforming         the first or second arcs or the straight section.

The straight section may be approximately parallel to the second side wall.

The entire length of the first arc and the entire length of the second arc with the straight section may define the mateable portions.

The first arc may curve in an arc of from 180° to 330° and may terminate in a hook section.

The channel may include longitudinal depressions.

The base of the channel may have a longitudinal corrugated or fluted profile.

Reinforcing flutes may be located on the side walls. The reinforcing flutes may run the length of the panels.

The straight section may terminate in an end that is configured to abut and may be restrained from rotating by the hook section when the second arc is nested into the first arc of an adjacent panel.

The length of the straight section may be configured to be received within and extend across the first arc of the adjacent panel.

According to a second aspect of the invention, there is provided an interlockable structural panel for forming roofs with a channel cross-section including:

-   -   a base and first and second side walls forming the sides of the         channel;     -   wherein the first and second side walls mirror each other's         extension from the base and provide a generally straight         extension from the base;     -   wherein a region adjoining an end of the first side wall distal         the base is curved as a first arc directed away from a central         portion of the channel and a section adjoining an end of the         second side wall is curved as a second arc directed towards the         central portion of the channel;     -   wherein a straight section extends from a distal end of the         second arc, the straight section being approximately parallel to         the second side wall; and     -   wherein the second side wall comprises at least first and second         intermediate arcs extending from a generally horizontal section         of the second sidewall and through a generally vertical section         of the second side wall intermediate the first and second         intermediate arcs, the second side wall extending distally from         the second intermediate arc is approximately parallel to the         extension of the second sidewall at its proximal end.

The entire length of the first arc and the entire length of the second arc with the straight section may define mateable portions arranged to engage with identical first and second arcs of an adjacent identical structural panel in a locking manner without deforming the first or second arcs or the straight section.

The first arc may terminate in a hook and the straight section may terminate in an end that may be configured to abut and be restrained from rotating by the hook when the second arc is nested into the first arc of an adjacent panel.

The length of the straight section may be configured to be received within and extend across the first arc of an adjacent panel.

The base may comprise a transverse crimp zone. The first and second side walls comprise respective sidewall crimp zones. The sidewall crimp zones may be tapered.

Either or both the first and second sidewalls may include a stiffening means comprising a stiffening flute. Each sidewall may comprise a plurality of stiffening flutes.

The second side wall extending distally from the second intermediate arc may be approximately parallel to the extension of the second sidewall at its proximal end.

The second arc may be arranged to nest within the first arc on an adjacent interlockable structural panel so that the two are locked together.

The first and second side walls may extend at an angle of approximately 45° to 60° with respect to the horizontal and to the base.

The second side wall extending distally from the second intermediate arc may be approximately parallel to the tangents and of the apex of the first and second intermediate arcs.

The first arc may be an arc of between 180° to 330°.

The second arc may be an arc of between 90° to 180°.

The first arc may terminate in a hook section.

The straight section extending from the second arc in one interlockable structural panel may be arranged to engage the ridge of the first side wall on a second interlockable structural panel that the second arc is nested with.

The channel may have longitudinal depressions. The base of the channel may have a longitudinal corrugated or fluted profile.

Reinforcing flutes may be located on the side walls. The reinforcing flutes may run the length of the panels.

The profiled interlockable structural panel of either the first or second aspects may comprise a plurality of crimp zones adapted to receive and be formed into transverse corrugations by complementary curvature rollers.

According to a third aspect of the invention, there is provided a roofing section comprising a plurality of the interlockable structural panels of the first or second aspects wherein the second arc of a first panel is nested into the first arc of an adjacent panel to lock the panels together.

According to a fourth aspect of the invention, there is provided a construction comprising a plurality of the interlockable structural panels of the first or second aspects.

According to a fifth aspect of the invention, there is provided a method of forming an interlockable structural panel for forming roofs with a channel cross-section comprising:

-   -   providing a panel profiling configuration comprising a plurality         of formations adapted to receive a sheet material;     -   rolling the sheet material through the panel profiling         configuration to form a profiled structural panel;     -   wherein panel profiling configuration comprises a plurality of         rollers adapted to form the sheet material to a profiled         interlockable structural panel as recited in the first or second         aspects.

The panel profiling configuration may be configured to form one or more longitudinal stiffening flutes in sidewalls of the profiled interlockable structural panel.

The method may further comprise:

-   -   providing a pair of complementary curvature rollers, each         curvature roller comprising a plurality of corrugating rods and         adapted to receive a profiled interlockable structural panel and         pass the profiled interlockable structural panel between the         complementary curvature rollers to form a plurality of         transverse corrugations in a portion of the profiled         interlockable structural panel, thereby to form a curved         profiled interlockable structural panel.

The transverse corrugations may be formed in the base of the profiled interlockable structural panel.

The method may further comprise providing a plurality of complementary curvature rollers pairs configured to form a plurality of transverse corrugations in a plurality of portions of the profiled interlockable structural panel.

The plurality of complementary curvature rollers pairs may be configured to form the transverse corrugations in the base and in one or more portions of the sidewalls of the profiled interlockable structural panel.

The depth of the transverse corrugations in the sidewalls of the profiled interlockable structural panel may decrease with distance from the base of the profiled interlockable structural panel.

The depth of the transverse corrugations in the sidewalls of the profiled interlockable structural panel may be tapered.

The profiled interlockable structural panel may comprise a plurality of crimp zones adapted to receive and be formed into transverse corrugations by the plurality of complementary curvature rollers.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the present invention are more fully described in the following description of several non-limiting embodiments thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings in which:

FIG. 1 is a cross section of a prior art panel;

FIG. 2 is a perspective of a single panel with normal cross-section of interlocking building panels according to a first embodiment of the present invention;

FIG. 3 is a sectional cross-section of the joining of the interlocking building panels of FIG. 2 ;

FIG. 3A is a sectional cross-section of the joining of a further embodiment of interlocking building panels with increased sidewall stiffness;

FIG. 3B is a perspective view of a plurality of interlocking building panels shown in use;

FIG. 3C is a further perspective view of a plurality of flattened interlocking building panels shown in use with edge restraint;

FIG. 4 is a perspective of the flattened interlocking building panels of FIG. 2 ;

FIG. 5 is a cross-section of the joining of adjacent panels flattened as in FIG. 3A;

FIG. 6 is a perspective view of a single panel with normal cross-section of interlocking building panels according to a second embodiment of the present invention;

FIG. 7A shows a sectional cross-section of a further embodiment of interlocking building panels;

FIG. 7B shows a detail view of the joining between adjacent panels of FIG. 7A;

FIG. 8A shows a sectional cross-section of a further embodiment of interlocking building panels comprising a plurality of stiffening means in the panel sidewalls;

FIG. 8B shows a shows a detail view of the interlocking joining of adjacent panels of FIG. 8A;

FIG. 8C shows a shows a shows a detail view of the corrugated/fluted base of the panel of FIG. 8A;

FIG. 9A shows a schematic depiction of a curvature roller configuration for forming curved panels;

FIG. 9B shows a detail view of a curved panel comprising a plurality of transverse corrugations in the base and sidewalls of the panel;

FIG. 10A shows a schematic depiction of a curvature roller configuration comprising a plurality of curvature roller pairs for forming curved panels;

FIG. 10B shows an alternate configuration of a profiled panel with a flat base; and

FIGS. 11A and 11B show examples of an arched roof construction formed from a plurality of longitudinally-curved interlocking panels of the previous panel embodiments.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1 of the figures, a prior art interlockable building panel 33 is shown. The interlockable building panel 33 includes male rib 36 and female rib 34. The interlockable building panel also includes a first projection 37 proximate the male rib 36 and a second projection 35 proximate the female rib 34. Where adjacent panels 33 are interlocked, the male rib 36 in one panel 33 engages into the female rib 34 in the adjacent panel 33. Additionally, the first projection 37 in one panel 33 nests with the second projection 35 in another panel 33 that the one panel is interlocked with. Due to the U-shaped profiles of the male and female ribs 36, 34, when the two are interlocked there is minimal give for deformation. Therefore, when the panels 33 are flattened the male rib 36 has a tendency to spring out of the female rib 34. The common solution to this has been to fasten the female rib to the male rib with screws which defeats the self interlockable of adjoining panels and adds to the cost of construction.

With reference to FIGS. 2 to 5 , interlockable structural panels 4 according to a first embodiment of the present invention are shown. The panels 4 are arranged as channels with a base 3, a first side wall 55 and a second side wall 53 extending from the base 3, both with a component of vertical extension to form the channel. The first and second side walls 55, 53, mirror each other in their generally straight extension from the base. The end of the first side wall 55 is arranged as a first arc 13 that curves away from the centre of the channel and the end of the second wall 53 is arranged as a second arc 23 that curves towards the centre of the channel. Two or more interlockable panels 4 are connected together by nesting the second arc 23 of one interlockable panel 4 into a first arc 13 of an adjacent interlockable panel 4.

The first side wall 55 includes a base extension 1 that extends from the base 3. A first section 11 extends from the base extension 1 at an angle closer to the horizontal than the base extension 1. In one embodiment the first section is at an angle between 0° and 45° to the horizontal. A second section 12 extends from the first section 11 and is at an angle closer to the vertical than the first section 11. In one embodiment the second section is at an angle of between and 90° to the horizontal. The first side wall 55 extends generally straight from the base 3 as illustrated in the Figures.

Extending from the second section 12 is a first arc 13 that is curved away from the centre of the channel of panel 4. The end of the arc 13 is arranged as a hook that includes a projection at its distal tip that extends towards the first side wall 55.

In an alternative embodiment the end of the arc 13 includes an alternative arrangement hook 14 that still projects towards the first side wall 55. This can be a folded or straight section or otherwise as understood by the skilled addressee.

The second side wall 53 extends from the base 3 opposite first wall 55. The second side wall 53 includes a second base extension 2. A third section 21 extends from the second base extension 2. In one embodiment the third section is angled from the horizontal between 135° and 180°. A fourth section 22 extends from the third section 21 and is at an angle closer to the vertical than the third section 21. In one embodiment the fourth section is at an angle of between and 150° to the horizontal. The second side wall 53 extends generally straight from the base 3 as illustrated in the Figures.

Extending from the fourth section 22 is a second arc 23 that is curved towards the centre of the channel of panel 4. The end of the arc 23 is arranged as a straight section 24 running approximately parallel to the fourth section 22. The straight section 24 is of a length to be received within the first arc 13. The end of the straight section 24 is arranged to abut and be restrained by the projection 15 of hook 14 at the end of arc 13 when the second arc 23 is nested into a first arc 13 of an adjacent panel 4.

FIG. 3 illustrates the joining of one interlockable panel 4 with another. Arc 23 of second side wall 53 nests inside arc 13 of the first side wall 55. The straight section 24 extends and its end is restrained from rotating by hook 14. Arc 13 acts as a female mating section to receive arc 23. As detailed in FIGS. 3 and 5 , first side wall 55 is formed with first section 11 extending form the base extension, the first section 11 is angled at 15° to the horizontal connecting to a further section 12 angled at 60° to the horizontal and connecting to a section 13 curving in an arc of 270°. Section 13 terminates in a hook section 14.

Also as detailed in FIG. 3 , second side wall 53 is formed with third section 21 angled at 165° to the horizontal connecting to fourth section 22 angled at 120° to the horizontal and connecting to a section 23 curving in an arc of 130°. Section 23 connects to a straight section 24 such that sections 23 and 24 nest inside section 13 of base extension 1.

In a further embodiment, FIG. 3A shows the joining of one interlockable panel 5 with another, where panel 5 is an improved panel 5 of panel 4 having increased panel strength. First and second side walls 55 and 53 extend generally straight from base 3 at an angle of approximately 45° to the horizontal.

Section 21 in second side wall 53 of panel 4, as shown in FIG. 3 , is replaced with a horizontal section 60 in second side wall 53 of panel 5 in the further embodiment of FIG. 3A. Horizontal section 60 leads into new additional intermediate arc sections 61 and 62 in second side wall 53 interspaced with a substantially vertical section 63. Intermediate arc sections 61 and 62 may have the same or approximately equal radii of curvature. Intermediate arc sections 61 and 62 form a longitudinal flute (similar to flute portions 100 of FIGS. 7B, 8A or flutes 57, 58 of FIG. 10A) along the length of panel 5 to provide additional strength to sidewall 53 to realise a stiffened sidewall 53.

Further straight section 22 extending to the distal end of second side wall 53 is also aligned at approximately 60 degrees to horizontal section 60 and to base 3, before leading into male arc section 23 of second side wall 53. Section 22 in most embodiments will be aligned at approximately 60° to horizontal section 60 and to base 3. Section 22 extends away from intermediate arc sections 61 and 62 approximately parallel to the second side wall 53 such that straight section 2 of panel 5 also extends away from the base 3 of panel 5 at approximately 45 degrees to the horizontal depending on the cover width of the panel 4 as desired. In some embodiments, sections 11 and 60 are aligned at about 15° to base 3 which would provide a cover width of about 650 mm. In alternate embodiments, for the same precursor sheet material coil, sections 11 and 60 are aligned approximately horizontal to base 3 which would provide a cover width of about 800 mm. Straight section 22 also is approximately parallel to the tangents 64 and 65 of the apex of intermediate arcs 61 and 62 respectively.

As before, first side wall 55 of panel 5 is formed with first section 1 extending form the base extension, and includes a generally horizontal section 11 which connects to further section 12. However, in panel 5, first and second side walls 55 and 53 are each disposed at an angle of either about 45° or about 60° from the horizontal with respect to base 3. Section 12, as before connects to a female arc section 13 curving in an arc of 270°. Section 13 terminates in a hook section 14.

When engaged with an adjacent panel 5, arc 23 nests inside arc 13 of first sidewall 55. Similarly, arc 13 acts as a female mating section to receive arc 23 and straight section 24 extends and its end is restrained from rotating by hook 14 as before with panel 4.

As can be seen in FIG. 3A, the stiffening of the side walls by intermediate arc sections 61 and 62 is only necessary in second side wall 53 which includes male arc section 23. The advantage of the stiffened male sidewall 53 is realised in increased strength in panel 5, especially at the edge of the roof where male arc section 23 defines the roof extremity of a collection of many panels 5.

The stiffened sidewall 53 provides increased strength to the end panel when a pipe section 71 is inserted into arc section 23 along the length of panel 5 and secured to adjacent panel with edge restraints 70 as seen in FIG. 3B and FIG. 3C. Edge restraints 70 are secured by a bolt or screw fastener through arc section 23 of stiffened sidewall 53 to the pipe section inserted through arc section 23.

In use in a particular arrangement, panel 5 may be used in conjunction with a plurality of panels 4 to form a roof, whereby the finished roof comprises a plurality of interlocked panels 4 and a single panel 5 at the extreme edge of the roof interlocked with an adjacent one of panels 4 such that the roof edge has increased strength arising from stiffened sidewall 53 of the edge panel 5 when tied to adjacent interlocked panel 4 with edge restraints 70.

FIG. 5 shows a panel in which the channel profile of panel 4 has been flattened to provide greater horizontal coverage. This is particularly advantageous for roofs where the span admits of self-supporting panels where a lesser second moment of bending is adequate. The second moment of bending is proportional to the square of the depth of the channel. The latter may be strengthened by pressing longitudinal depressions into the sheet material.

FIG. 4 shows how the joint geometry of first and second side walls 55, 53 of panel 4 accommodates the flattening of first and second side walls 55, 53 with the integral nesting of sections 23 and 24 inside section 13 being maintained. Similarly, as shown in FIG. 3C, the joint geometry of first and second side walls 55, 53 of panel 5 accommodates the flattening of first and second side walls 55, 53 with the integral nesting of sections 23 and 24 inside section 13 being maintained. Accordingly, the integrity of the joint minimizes the need for fasteners which are required in prior art panels. As the second side wall 53 flexes and arc 23 attempts to rotate, the straight section hits the projection 15 of hook 14 and is restrained from rotating and slipping out of arc 13.

FIGS. 2 and 4 show the interlockable panels 4 interlocked to form a single roof section.

With reference to FIG. 6 a second embodiment of the present invention is shown. For convenience features of the interlockable panel 44 that are similar or correspond to features of the interlockable panel 4 of the first embodiment have been referenced with the same reference numerals.

Interlockable panel 44 includes a base 43 in place of base 4 for panel 4. The base 43 is of a waved profile to strengthen the base 43.

In an alternative embodiment, ridges or fluting are formed along the length of the first and second side walls for reinforcement. The ridges or fluting can be located along the first or second base extensions 1, 2, or the second or fourth sections 12, 22.

FIG. 7A shows a further embodiment of interlockable panel 80. The panels 80 are arranged as channels with a base 81, a first side wall 82 and a second side wall 83 extending from the base 81, both with a component of vertical extension to form the channel, extending generally straight from base 81 at an angle of approximately either about 45° or about 60° to the horizontal. In particular arrangements, the angle of sidewalls 82 and 83 may be about 50° to about 60° to the horizontal. In alternate arrangements, the angle of sidewalls 82 and 83 may be about 30° to about 45° to the horizontal. It will be appreciated that a shallower angle of the sidewalls to the horizontal provides for a wider panel 80 such that a larger roof span can be achieved with a smaller total number of interconnected panels 80 compared with panels having a greater sidewall angle. However, shallower panels are not as strong as deeper panels, hence for larger total roof spans, panels 80 having a deeper profile are preferred at the expense of requiring more individual panels to form the total roof area per specifications. The first and second side walls 82, 83, mirror each other in their generally straight extension from the base. First and second side walls 82, 83 include horizontal sections 84 and 85 respectively. Similarly to panel 5 of FIG. 3A, sidewall 82 of improved pane 80 includes intermediate arc sections 86 and 87 interspaced with generally vertical section 88. Intermediate arc sections 86 and 87 may have the same or approximately equal radii of curvature Intermediate arc sections 86 and 87 provide additional strength to sidewall 82 to realise a stiffened sidewall 82. Further straight section 89 extending to the distal end of second side wall 82 is aligned at approximately 60 degrees to horizontal section 84 and to base 81, before leading into male arc section 90 of second side wall 82. Intermediate arc 87 in conjunction with generally straight sections 88 and 89 either side of arc 87 form a stiffening flute 100 formed in the panel profile and extending longitudinally along the length of panel 80 (i.e. into the page in FIG. 7A).

The end of the first side wall 82 is arranged as a male arc section 90 that curves toward the centre of the channel. The end of the second wall 83 is arranged as a female arc section arc 91 that curves away from the centre of the channel. Female arc section 91 terminates in a hook section 94. Two or more interlockable panels 80 are connected together by nesting the male arc section 90 of one interlockable panel 80 into a female arc section 91 of an adjacent interlockable panel 80. The end of the male arc section 90 is arranged as a straight section 92 which is of a length to be received within the female arc section 91 of an adjacent panel 80. Section 92 is, at the distal end, bent away from the centre of arc 90 to form a barb 93. The barb 92 is arranged to abut and be restrained by hook section 94 at the end of female arc section 91 when the male arc section 90 is nested into a female arc 91 of an adjacent panel 80.

Panel 80 includes a plurality of crimp zones to enable the panel to be formed into curved panels where a curve to panels 80 is applied longitudinally (i.e. into the page with respect to FIG. 7A).

Embodiments of the building panels as described herein are formed, typically on site, by passing a sheet of metal material (e.g. aluminium) of a desired width through a series of profiling rollers configured to bend the sheet in the direction perpendicular to the longitudinal length of the coiled sheet metal into the desired panel profile (e.g. as shown in the Figures). Sheet material typically is delivered to the constructions site as a large coil of sheet material of the desired width for formation of the panels which are rolled through the series of profiling rollers to the desired length.

As can be seen in FIG. 7A, base 81 of panel 80 includes a crimp zone 95, and first and second side walls 82 and 83 respectively include sidewall crimp zones 96 and 97. Sidewall crimp zones 96 and 97 are tapered such that the proximal end (nearest to base 81) is deeper than at the distal ends (farthest from base 81) of sidewall crimp zones 96 and 97.

Referring to FIG. 7B, first sidewall 82 also includes a stiffening means, shown in FIG. 7B as a stiffening flute 98. Stiffening flute 98 is shown located about intermediate arc 87 extending into generally straight sections 88 and 89 and acts to further increase the strength of sidewall 82. Stiffening flutes are formed in the same manner as the predetermined profile of finished panels, e.g. 4, 5, 80, by profiling rolls that are integral to the machine which forms the panel profiles as shown in the attached figures, e.g. FIG. 4 and FIG. 6 . Stiffening flutes comprise a shallow groove running along a surface in the longitudinal direction of the formed & profiled panels. For example, in FIG. 3A the combination of intermediate arc sections 61 and 62 and straight sections 60 and 63 either side of arc 61 form one strengthening flute of profiled panel 5. In alternate arrangements, the second sidewall 83 may include a stiffening means as shown in FIG. 8A, or both first and second sidewalls 82 an 83 may comprise respective stiffening means comprising a respective stiffening flute. Sidewalls 82 and/or 83 may additionally each comprise more than one stiffening means including stiffening flutes 100 as shown in FIGS. 8A and 8B. Stiffening flutes 100 run longitudinally along the sidewalls for the length of the panel 80.

Panel 80 may also include corrugated or fluted sections 101 in base 81 as shown in FIGS. 8A and 8C which also run longitudinally along the base for the length of the panel 80.

Once profiled in the profiling rollers and cut to length, longitudinally curved panels are formed by passing the profiled panels through a separate series of curvature rollers 101 and 102 which exert a pressure to both the top and bottom sides of the profiled panel as shown in curvature roller configuration 900 of FIG. 9A. FIG. 9A shows a cross section of a previously profiled panel 80, shown along central axis of the base 81 (seen as axis A-A of FIG. 3C). Complementary curvature rollers 101 and 102 each comprise a plurality of corrugating rods 103 disposed regularly about the circumference of curvature rollers 101 and 102. Curvature rollers 102 and rods 103 are aligned such that as the rollers turn, drawing panel through and between curvature rollers 101 and 102, respective corrugating rods 103 engage the panel 80 intermediate to two adjacent corrugating rolls of the complementary curvature roller. Profiled panel 80 is drawn through the curvature rollers which apply a small transverse corrugation 110 to panel 80 in the longitudinal direction to form a curved panel 80A (transverse corrugations 110 shown exaggerated) emerging from curvature roller pair 102 and 103. FIG. 9B depicts a partial perspective view of curved profiled panel 80A having a flat base 81 and a plurality of transverse corrugations 110 a formed in base 81 (i.e. by curvature roller pair 102 and 103 of FIG. 9A) and further transverse corrugations 100 b in sidewalls 82 and 83 (formed by additional curvature roller pairs arranged to engage sidewalls 82 and 83 respectively as shown, for example, in FIG. 10A). Curved panel 80A emerges from curvature roller pair 102, 102 with a predetermined curvature 105 which, when interlocked with like curved panels 80A, form a curved roof structure 1100, for example, as seen in FIGS. 11A and 11B. In further arrangements, a plurality of curved panels formed by the methods described herein may be used for constructions including roofs, walls, and the like.

In a typical arrangement, the transverse corrugations 110 have a corrugation pitch 111 of the order of about 30-60 mm, typically about 40 mm, and a corrugation depth 113 of the order of about 4-6 mm, typically about 5 mm. Curvature rollers 101, 102 have the effect of shortening the bottom edge of profiled panel 80 by about 10 mm per metre with respect to the top edge of panel 80. However, it will be appreciated that corrugations of different pitch and/or depth may be applied to panel 80 to achieve a curved panel 80A having a desired panel curvature.

FIG. 10A shows a depiction of a curvature profiling configuration 1000 to accept a profiled panel 50 (i.e. similar to previously described panels 4, 5, 80 etc. above) and to apply a transverse corrugation along the length of the panel to form a curved, profiled panel. As per panel 80 shown in FIG. 7A, profiled panel 50A is formed with a plurality of crimp zones 52, 54, and 56, respectively in the base 51, and first and second sidewalls 55 and 53. Panel 50A is depicted comprising a plurality of flute formations 57 and 58 respectively in sidewalls 53 and 55 as additional strengthening features of panel 50A. A plurality of curvature roller pairs 220-230 are configured to apply transverse corrugations to profiled panel 50A. Plurality of curvature rollers 220-230 are positioned with respect to panel 50A to preserve flute formations 57 and 98 as panel 50A is being curved. Each curvature roller pairs 220-230 comprises a pair of complementary curvature rollers 101 and 102 as shown in FIG. 9A, respectively engaging the top and bottom surfaces of panel 50A (Note that, as depicted in FIG. 10A, curvature roller pair 220 is located behind curvature roller pairs 228 and 229). Crimp zones 52, 54, and 56 enable the panel 50A to be formed into a curved panel by curvature roller pairs 220-230. In particular arrangements, the pitch of the transverse corrugations formed in base 51 of panel 50A by curvature configuration 200 is about 40 mm with a depth of about 5 mm as described above. Transverse corrugations formed in sidewalls 53 and 55 may decrease in depth along the sidewalls where the sidewall corrugations nearest to base 51, for example provided by curvature roller pairs 228 and 230, may have a similar depth to the transverse corrugations formed in base 51 (i.e. about 5 mm depth), and decreasing in depth along the sidewalls 53 and 55 further from the base 51. For example, the depth of the transverse corrugations formed by curvature rollers 226 and 227 farthest from base 51 may be significantly less than the depth of the transverse corrugations formed in base 51 and may taper to zero depth at the extremities of sidewalls 53 and 55. The reduction in transverse corrugation depth along the sidewalls may be smoothly decreasing with distance from base 51. To facilitate such a smooth tapering of the transverse corrugation depth along the sidewalls, crimp zones 54, and 56 may be tapered similar to tapered crimp zones 96, and 97 depicted in FIG. 7A.

Panel 50A of FIG. 10A is shown in a first optional embodiment comprising additional optional complementary strengthening flutes 59 in sidewalls 53 and 55. In an alternate embodiment, shown in FIG. 10B, panel 50B comprises a wider and flat base 51B compared with base 51 where flat base 51B does not include optional strengthening flutes 59. It will be appreciated that, when forming a curved longitudinal profile of a panel 50B, an alternate configuration of curvature rollers 220 to 230 would be used. For instance, in this particular example of panel 50B, shown in FIG. 10B to scale with panel 50A above, curvature roller pairs 228 and 230 are not required and curvature roller pair 220 may be substituted for wider roller pair 220A to engage a wider base 51B of panel 50B.

Variations and Modifications

It will be realized that the foregoing has been given by way of illustrative example only and that all other modifications and variations as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.

In this specification, adjectives such as first and second, left and right, top and bottom, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where the context permits, reference to an integer or a component or step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step etc.

The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The invention is intended to embrace all alternatives, modifications, and variations of the present invention that have been discussed herein, and other embodiments that fall within the scope of the above-described invention. 

1. An interlockable structural panel for forming roofs with a channel cross-section including: a base and first and second side walls forming the sides of the channel; wherein the first and second side walls mirror each other's extension from the base and provide a generally straight extension from the base; wherein a region adjoining an end of the first side wall distal the base is curved as a first arc directed away from a central portion of the channel and a section adjoining an end of the second side wall is curved as a second arc directed towards the central portion of the channel; wherein a straight section extends from a distal end of the second arc; wherein the end of the first arc comprises a projection, a distal tip of the projection extending towards the first side wall; wherein the second side wall comprises at least first and second intermediate arcs extending from a generally horizontal section of the second sidewall and through a generally vertical section of the second side wall intermediate the first and second intermediate arcs; and wherein the structural panel includes mateable portions arranged to engage with identical first and second arcs of an adjacent identical structural panel in a locking manner without deforming the first or second arcs or the straight section.
 2. The interlockable structural panel as claimed in claim 1, wherein the straight section is approximately parallel to the second side wall.
 3. The interlockable structural panel as claimed in either claim 1 or claim 2, wherein the entire length of the first arc and the entire length of the second arc with the straight section may define the mateable portions.
 4. The interlockable structural panel as claimed in any one of claims 1 to 3, wherein the second side wall extending distally from the second intermediate arc is approximately parallel to the extension of the second sidewall at its proximal end.
 5. The interlockable structural panel as claimed in claim 1, wherein the second arc is arranged to nest within the first arc on an adjacent interlockable structural panel so that the two are locked together.
 6. The interlockable structural panel as claimed in claim 1, wherein the first and second side walls extend at an angle of approximately 45° to 60° with respect to the horizontal and to the base.
 7. The interlockable structural panel as claimed in claim 1, wherein the second side wall extending distally from the second intermediate arc is approximately parallel to tangents apexes of the first and second intermediate arcs.
 8. The interlockable structural panel as claimed in claim 1, wherein the first arc is an arc of between 180° to 330°.
 9. The interlockable structural panel as claimed in claim 1, wherein the second arc is an arc of between 90° to 180°.
 10. The interlockable structural panel as claimed in any one of the preceding claims, wherein the first arc terminates in a hook section.
 11. The interlockable structural panel as claimed in claim 10, wherein the straight section extending from the second arc in one interlockable structural panel is arranged to engage the projection of the first side wall on a second interlockable structural panel that the second arc is nested with.
 12. The interlockable structural panel as claimed in claim 1, wherein the channel has longitudinal depressions.
 13. The interlockable structural panel as claimed in claim 1, wherein base of the channel has a longitudinal corrugated or fluted profile.
 14. The interlockable structural panel as claimed in claim 1, wherein reinforcing flutes are located on the side walls.
 15. The interlockable structural panel as claimed in claim 14, wherein the reinforcing flutes run the length of the panels.
 16. The interlockable structural panel as claimed in claim 10, wherein the straight section terminates in an end that is configured to abut and be restrained from rotating by the hook section when the second arc is nested into the first arc of an adjacent panel.
 17. The interlockable structural panel as claimed in claim 1, wherein the length of the straight section is configured to be received within and extend across the first arc of the adjacent panel.
 18. An interlockable structural panel for forming roofs with a channel cross-section including: a base and first and second side walls forming the sides of the channel; wherein the first and second side walls mirror each other's extension from the base and provide a generally straight extension from the base; wherein a region adjoining an end of the first side wall distal the base is curved as a first arc directed away from a central portion of the channel and a section adjoining an end of the second side wall is curved as a second arc directed towards the central portion of the channel; wherein a straight section extends from a distal end of the second arc, the straight section being approximately parallel to the second side wall; and wherein the second side wall comprises at least first and second intermediate arcs extending from a generally horizontal section of the second sidewall and through a generally vertical section of the second side wall intermediate the first and second intermediate arcs, the second side wall extending distally from the second intermediate arc is approximately parallel to the extension of the second sidewall at its proximal end.
 19. The interlockable structural panel as claimed in claim 18, wherein the entire length of the first arc and the entire length of the second arc with the straight section define mateable portions arranged to engage with identical first and second arcs of an adjacent identical structural panel in a locking manner without deforming the first or second arcs or the straight section.
 20. The interlockable structural panel as claimed in claim 18, wherein the first arc terminates in a hook and the straight section terminates in an end that is configured to abut and be restrained from rotating by the hook when the second arc is nested into the first arc of an adjacent panel.
 21. The interlockable structural panel as claimed in claim 18, wherein the length of the straight section is configured to be received within and extend across the first arc of an adjacent panel.
 22. The interlockable panel of any one of the preceding claims, wherein the base comprises a transverse crimp zone.
 23. The interlockable panel of any one of the preceding claims, wherein the first and second side walls comprise a respective sidewall crimp zone.
 24. The interlockable panel of any one of the preceding claims, wherein the sidewall crimp zones are tapered.
 25. The interlockable panel of any one of the preceding claims, wherein either or both the first and second sidewalls include a stiffening means comprising a stiffening flute.
 26. The interlockable panel of claim 25, wherein each sidewall comprises a plurality of stiffening flutes.
 27. The interlockable panel of any one of the preceding claims, wherein the second side wall extending distally from the second intermediate arc is approximately parallel to the extension of the second sidewall at its proximal end.
 28. The interlockable panel of any one of the preceding claims, wherein the second arc is arranged to nest within the first arc on an adjacent interlockable structural panel so that the two are locked together.
 29. The interlockable panel of any one of the preceding claims, wherein the first and second side walls extend at an angle of approximately 45° to 60° with respect to the horizontal and to the base.
 30. The interlockable panel of any one of the preceding claims, wherein the second side wall extending distally from the second intermediate arc is approximately parallel to the tangents and of the apex of the first and second intermediate arcs.
 31. The interlockable panel of any one of the preceding claims, wherein the first arc is an arc of between 180° to 330°.
 32. The interlockable panel of any one of the preceding claims, wherein the second arc is an arc of between 90° to 180°.
 33. The interlockable panel of any one of the preceding claims, wherein the first arc terminates in a hook section.
 34. The interlockable panel of any one of the preceding claims, wherein the straight section extending from the second arc in one interlockable structural panel is arranged to engage the ridge of the first side wall on a second interlockable structural panel that the second arc is nested with.
 35. The interlockable panel of any one of the preceding claims, wherein the channel has longitudinal depressions.
 36. The interlockable panel of any one of the preceding claims wherein the base of the channel has a longitudinal corrugated or fluted profile.
 37. The interlockable panel of any one of the preceding claims, wherein reinforcing flutes are located on the side walls.
 38. The interlockable panel of claim 37 wherein the reinforcing flutes run the length of the panels.
 39. The interlockable panel of any one of the preceding claims, further comprising a plurality of crimp zones adapted to receive and be formed into transverse corrugations.
 40. A roofing section comprising a plurality of the interlockable structural panel of any one of claims 1 to 39, wherein the second arc of a first panel of the plurality of panels is nested into the first arc of an adjacent panel of the plurality of panels to lock the panels together.
 41. A construction comprising a plurality of the interlockable structural panels of any one of claims 1 to
 39. 42. A method of forming an interlockable structural panel for forming roofs with a channel cross-section comprising: providing a panel profiling configuration comprising a plurality of formations adapted to receive a sheet material; and rolling the sheet material through the panel profiling configuration to form a profiled structural panel; wherein panel profiling configuration comprises a plurality of rollers adapted to form the sheet material to a profiled interlockable structural panel as claimed in any one of claims 1 to
 39. 43. The method of claim 42, wherein panel profiling configuration is configured to form one or more longitudinal stiffening flutes in sidewalls of the profiled interlockable structural panel.
 44. The method of claim 42, further comprising: providing a pair of complementary curvature rollers, each curvature roller comprising a plurality of corrugating rods and adapted to receive a profiled interlockable structural panel and pass the profiled interlockable structural panel between the complementary curvature rollers to form a plurality of transverse corrugations in a portion of the profiled interlockable structural panel, thereby to form a curved profiled interlockable structural panel.
 45. The method of claim 44, wherein the transverse corrugations are formed in the base of the profiled interlockable structural panel.
 46. The method of either claim 44 or claim 45, comprising providing a plurality of complementary curvature rollers pairs configured to form a plurality of transverse corrugations in a plurality of portions of the profiled interlockable structural panel.
 47. The method of claim 45, wherein the plurality of complementary curvature rollers pairs are configured to form the transverse corrugations in the base and in one or more portions of the sidewalls of the profiled interlockable structural panel.
 48. The method of claim 47, wherein the depth of the transverse corrugations in the sidewalls of the profiled interlockable structural panel decreases with distance from the base of the profiled interlockable structural panel.
 49. The method of either claim 47 or claim 48, wherein the depth of the transverse corrugations in the sidewalls of the profiled interlockable structural panel are tapered.
 50. The method of any one of claims 46 to 49, wherein the profiled interlockable structural panel comprises a plurality of crimp zones adapted to receive and be formed into transverse corrugations by the plurality of complementary curvature rollers. 